The performance evaluation of gamma- and neutron-sensitive superheated emulsion (bubble) detectors

The superheated emulsion (bubble) detectors have been developed at Defence Laboratory, Jodhpur (DLJ), India, for measurement of gamma doses. The developed detectors have been tested at Radiation Safety and System Division (RSSD), Bhabha Atomic Research Center (BARC), Mumbai (India) and DLJ having ISO-17025 accredited facility for testing and calibration of Radiation Monitors. A series of experiments were conducted to determine the gamma and neutron sensitivity of these detectors, i.e. batch homogeneity, reproducibility, dose equivalent rate effect, gamma/neutron dose equivalent response, gamma/neutron energy response and change in gamma sensitivity as a function of temperature. All the results were within +/- 20% of themselves. It is observed that the response of the detector is dependent upon temperature. The recommended ideal working temperature range of the detector is 20-28 degrees C, but a temperature correction is required beyond approximately 30 masculineC. The temperature compensation may be possible up to 45 degrees C in improved version using specially prepared reversible thermo-sensitive polymer gel. The detector may have applications in radio-diagnosis, R&D laboratories, and health physics as well as an indicator of gamma radiation for dirty bomb to be useful for first responder in any radiological emergency.